Full color organic electroluminescent device and method for fabricating the same

ABSTRACT

The present invention relates to a full color organic electroluminescent device and a method for fabricating the same and provides a full color organic electroluminescent device. The invention reduces misalignment errors caused by fine patterning of the emitting layer by reducing the steps of the fine patterning process. In particular, the blue emitting layer functions as a hole inhibition layer which results in superior color purity and improved stability for the color organic electroluminescent device. The use of such a blue emitting layer also reduces the manufacturing steps. The device comprises a substrate; a first electrode pattern formed on the substrate; a red emitting layer formed by patterning a red emitting material on a red pixel region of the first electrode pattern and a green emitting layer formed by patterning a green emitting material on a green pixel region of the first electrode pattern. A blue emitting layer is applied over the entire substrate, over the upper parts of the red and green emitting layers and a second electrode is formed on an upper part of the blue emitting layer.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.10/938,471, filed Sep. 9, 2004, which claims priority to and the benefitof Korean Patent Application No. 2003-63752, filed on Sep. 15, 2003, inthe Korean Intellectual Property Office, the entire contents of both ofwhich are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a full color organic electroluminescentdevice and a method for fabricating the full color organicelectroluminescent device, more particularly, to a full color organicelectroluminescent device with reduced pixel misalignment.

2. Description of Related Art

Generally, an organic electroluminescent device comprises various layersincluding an anode and a cathode, a hole injection layer, a holetransport layer, an emitting layer, an electron transport layer and anelectron injection layer. Organic electroluminescent devices areclassified as polymeric organic EL (electroluminescent) devices andsmall molecular organic EL (electroluminescent) devices according to thematerials used in making them. The respective layers are introduced byvacuum deposition for a small molecular organic EL device while apolymeric organic EL device is typically fabricated by a spin coatingprocess.

The small molecular organic EL device is completed by laying up amultilayer organic film including a hole injection layer, a holetransport layer, an emitting layer, a hole inhibiting layer and anelectron injection layer by deposition processes, and by finallydepositing the cathode electrode.

A small molecular organic EL device is fabricated by an existing processby depositing the hole injection layer and the hole transport layer ascommon layers, depositing red, green and blue colors on the holeinjection layer and the hole transport layer, patterning the red, greenand blue colors on the hole injection layer and the hole transport layerusing a shadow mask, sequentially depositing a hole inhibiting layer andan electron injection layer as common layers on the patterned red, greenand blue colors, and depositing the cathode on the hole inhibiting layerand the electron injection layer.

Mass production of a small molecular organic EL device is difficultsince such a full color device is fabricated by depositing therespective layers using masks. A fluorescent or phosphorescent device isfabricated by introducing the respective layers using vacuum deposition.Patents regarding full color devices include U.S. Pat. Nos. 6,310,360,6,303,238 and 6,097,147.

A polymeric organic electroluminescent full color device is fabricatedby patterning red, green and blue polymers. Such a polymeric organicelectroluminescent device tends to have problems in its emissioncharacteristics. In particular, it generally has lower emissionefficiency and reduced lifespan when fabricated using ink jet technologyor laser induced thermal imaging.

In order to apply a laser induced thermal imaging process to thefabrication of a full color polymeric organic electroluminescent device,at least a light source, a transfer film and a substrate are required.Light from the light source is absorbed by a light absorption layer ofthe transfer film so that the light absorbed into the light absorptionlayer of the transfer film is converted into thermal energy. A transferlayer forming material of the transfer film is transferred to thesubstrate by the thermal energy to form a desired image as disclosed inU.S. Pat. Nos. 5,220,348, 5,256,506, 5,278,023 and 5,308,737.

The laser induced thermal imaging can also be used to form patterns ofemitting materials as disclosed in U.S. Pat. No. 5,998,085.

U.S. Pat. No. 5,937,272 relates to a method for forming an advancedpatterned organic layer in a full color organic electroluminescentdevice in which a donor support is coated with a transferable organicelectroluminescent material. The donor support is heated so that theorganic electroluminescent material is transferred onto an object suchas a recessed surface portion of the subpixels of a thin film transistorto form a colorized organic electroluminescent medium.

Therefore, any process for forming an emitting layer is restricted sincefine patterning should be performed for each of the red, green and bluecolors to fabricate a full color organic electroluminescent device.

FIG. 1 is a cross sectional view illustrating structure of a full colororganic electroluminescent device according to prior art.

Referring to FIG. 1, the anode electrode is first patterned bydepositing an anode electrode 12 on a substrate 10. An insulation filmis applied to the substrate, and together with the anode electrodedefines a pixel region. Then, a pixel region is defined by an insulationfilm 14. A hole injection layer 16 is coated over the red, green andblue pixel regions by such a method as vacuum deposition and a holetransport layer 18 is applied over the hole injection layer.Alternative, the hole injection layer and hole transport layer can beapplied as a common layer. Red 100, green 200 and blue 300 are formed onan upper part of the hole transport layer 18 by vacuum deposition, spincoating or laser induced thermal imaging. Red, green and blue arepatterned using a shadow mask when using vacuum deposition. However, itis not particularly necessary to use the shadow mask when using a laserinduced thermal imaging method which transfers a desired part only.

A hole inhibition layer 20 is coated over the substrate, and an electrontransport layer 22 is coated over the hole inhibition layer.Alternatively, the hole inhibition layer and electron transport layercan be coated as a common layer. Finally, a cathode electrode 24 as anupper electrode is laid up on the electron transport layer 22.

Prior art devices often have misalignment problems since the patterningprocess requires at least three deposition or transfer steps whenforming the fine patterns of the red 100, green 200 and blue 300 on thepixel region. Furthermore, the hole inhibition layer is essentiallyrequired to be formed on an upper part of the emitting layer to preventmovement of the holes since the movement of holes is faster than themovement of electrons when using a phosphorescence emitting material asthe emitting material for forming red, green and blue, that is, whenusing a host and a phosphorescence material as dopant in the pixelregion.

SUMMARY

Therefore, in order to solve the foregoing problems of the prior art, inone embodiment of the present invention, a full color organicelectroluminescent device is provided that can be fabricated in fewersteps than are required for existing phosphorescence emitting devices. Amethod for fabricating the full color organic electroluminescent deviceis also provided.

In an embodiment of the invention, a full color organicelectroluminescent device is provided comprising a substrate; a firstelectrode formed on the substrate; a red emitting layer formed bypatterning red emitting material on a red pixel region and a greenemitting layer formed by patterning green emitting material on a greenpixel region, each formed of a phosphorescence emitting layer; a blueemitting layer formed over the entire substrate and over the upper partsof both the red emitting layer and the green emitting layer; and asecond electrode formed on an upper part of the blue emitting layer.

Furthermore, an embodiment of the present invention provides a methodfor fabricating a full color organic electroluminescent devicecomprising the steps of forming a patterned lower electrode on asubstrate and forming an insulation film between the pattern of thelower electrode so that pixel regions are defined. The insulation filmis superimposed at a part of both ends of the patterned lower electrode,and an emitting region is opened. A hole injection layer and a separateor combined hole transport layer are formed over the entire substrate.Red and green emitting regions are formed in the pixel region using ared phosphorescence emitting material and a green phosphorescenceemitting material, respectively. A blue emitting layer is then formed byapplying a blue emitting material as a common layer over the entiresubstrate. Finally, an upper electrode is formed over the entiresubstrate.

Also, an embodiment of the present invention provides a full colororganic electroluminescent device comprising: a substrate; a firstelectrode pattern formed on the substrate; a red emitting layer formedby patterning red emitting material on a red pixel region and a greenemitting layer formed by patterning green emitting material on a greenpixel region which are formed on the first electrode; a blue emittinglayer formed over the entire substrate including the upper parts of thered emitting layer and the green emitting layer and formed of a blueemitting material having a larger energy band gap than the red emittingmaterial and the green emitting material; and a second electrode formedon an upper part of the blue emitting layer. Preferably, the blueemitting material has an HOMO value of at least |5.5 eV|.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other features and advantages of the present inventionwill become more apparent to those of ordinary skill in the art bydescribing in detail preferred embodiments thereof with reference to theattached drawings in which:

FIG. 1 is a cross sectional view showing the structure of a full colororganic electroluminescent device according to the prior art;

FIG. 2 is an energy band diagram for a conventional greenphosphorescence emitting material;

FIG. 3 is an energy band diagram for a green phosphorescence emittingmaterial using a blue emitting material as a common layer according tothe present invention;

FIG. 4 is a cross sectional view showing the structure of an organicelectroluminescent device according to one embodiment of the presentinvention;

FIG. 5 is a graph showing the relationship between bias voltage andluminance applied for test cells fabricated according to test example 2and comparative example 2; and

FIG. 6 is a graph for showing the relationship between bias voltage andcurrent density applied for test cells fabricated according to testexample 2 and comparative example 2.

DETAILED DESCRIPTION

The present invention will now be described in detail in connection withvarious embodiments with reference to the accompanying drawings. Forreference, like reference characters designate corresponding partsthroughout several views.

FIG. 2 is an energy band diagram where only a phosphorescence emittingmaterial is used as the conventional green emitting material, and FIG. 3is an energy band diagram where a phosphorescence emitting material isused as the green emitting material and a blue emitting material is usedas a common layer according to the present invention.

A phosphorescence emitting device in which an existing phosphorescenceemitting material is used as an emitting layer comprises a holeinjection layer 16 and a hole transport layer 18 formed of a smallmolecular material in a lower part of the phosphorescence emittingdevice. The emitting layer is formed with red, green and blue bypatterning an emitting layer on the hole injection layer 16 and the holetransport layer 18.

For a green phosphorescence emitting device, color purity deterioratesas the holes are transferred to the electron transport layer 22. Theholes are transferred to the electron transport layer where theelectrons and holes combine with each other in the emitting layer toproduce an exciton since the highest occupied molecular orbital (HOMO)value of the emitting layer 200 is 5.80 eV which is higher than the HOMOvalue of the electron transport layer 22 which is 5.78 eV.

Therefore, although the electron transport layer 22 can be introducedright after forming an emitting layer for a fluorescence emitting devicein which a fluorescence emitting material is used as the emitting layer,a hole inhibition layer having a HOMO value higher than the emittinglayer 200 is required for a green phosphorescence emitting device.

In order to inhibit the transferring of the holes to the electrontransport layer 22 and increase color purity, a hole inhibition layer 20is introduced between the emitting layer and the electron transportlayer 22. The hole inhibition layer 20 has a HOMO value of 5.92 eV.

According to an embodiment of the invention as shown in FIG. 4, while ahole injection layer 16 and a hole transport layer 18 are used accordingto the prior art, a blue emitting layer 300 forms both a fluorescencematerial and is layered on the upper parts of the red and greenphosphorescence emitting layers 100, 200 as a common layer to preventholes from transferring to the electron transport layer. Therefore,while a separate hole inhibition layer 20 is shown, it is not required.

Referring to FIG. 3, it can be seen that similar results are obtainedfrom the blue emitting layer 300 compared to the hole inhibition layer20 as illustrated in FIG. 2 since the blue emitting layer 300 introducedbetween the green emitting layer 200 and electron transport layer 22 asa common layer has a higher HOMO value of 5.85 eV compared to a HOMOvalue of 5.80 eV for the green emitting layer 200, thereby inhibitingthe transfer of holes.

It is preferable that the blue emitting layer is a blue fluorescenceemitting layer.

Although the green phosphorescence emitting layer 200 is described aboveas an example, an explanation of the red phosphorescence emitting layer100 is omitted since the same effect is obtained for a redphosphorescence emitting layer 100.

Also, although the blue fluorescence emitting material is described inthe above example as a blue emitting layer 300, a blue emitting materialhaving a larger energy band gap than the red emitting material and thegreen emitting material can also be used. It is preferred that the blueemitting material has a HOMO value of at least |5.5 eV|.

Referring again to FIG. 4, an embodiment of the present invention usingthe principle is illustrated in a cross sectional view showing thestructure of a full color organic electroluminescent device according toone embodiment of the present invention. The lower electrode 12 ispatterned on the lower substrate 10. A metallic reflective film is usedas the lower electrode for a front emission structure while atransparent material such as ITO or IZO is used to form a transparentelectrode for a rear emission structure. An insulation film (PDL) 14 fordefining the pixel regions is then formed on the lower electrode. Afterforming the insulation film on the lower electrode, a hole injectionlayer 16 and/or a hole transport layer 18 using an organic film areformed over the entire substrate.

The organic film is formed of small molecules such as CuPc, TNATA, TCTAand TDAPB and polymers such as PANI and PEDOT are used as an ordinaryhole injection layer, and the hole transport layer is formed of smallmolecules such as NPB, TPD, s-TAD, MTADATA, arylamine, hydrazone,stylbene and star burst based small molecules, and polymers such as PVK,carbazole, arylamine, perylene and pyrrole based polymers.

A pixel region is formed by patterning red phosphorescence emittingmaterial and green phosphorescence emitting material on the red 100 andgreen 200 regions in the pixel region after forming a hole injectionlayer 16 and/or a hole transport layer 18.

The red phosphorescence emitting material is a phosphorescence emittingmaterial which is doped with a material capable of emittingphosphorescence in the triplet state. The red emitting material consistsof a host that is a material capable of transferring energy to aphosphorescence dopant, wherein the host is selected from the groupconsisting of carbazole, arylamine, hydrazone, stylbene, star burstbased derivatives such as CBP, and combinations thereof, and the dopantis an organic complex of a metal selected from the group consisting ofIr, Pt, Eu and Tb. An example is PtOEP. The green phosphorescenceemitting material is a phosphorescence emitting material doped with amaterial capable of emitting phosphorescence in the triplet state. Thegreen emitting material consists of a host comprising CBP and a dopantthat is an organic complex of a metal selected from the group consistingof Ir, Pt, Eu and Tb. An example is IrPPY.

A phosphorescence emitting material in which the host is doped with 7 to15 wt. % of dopant is used as the red phosphorescence emitting material.A phosphorescence emitting material in which host is doped with 5 to 10wt. % of dopant is used as the green phosphorescence emitting material.

When using vacuum deposition, the red and green material are finelypatterned using shadow masks. When using spin coating or laser inducedthermal imaging, it is not necessary to pattern the red and greenmaterials using shadow masks.

The thickness of the red emitting layer 100 is preferably 100 to 1,000Å. The emission efficiency is lowered due to an insufficientrecombination region of the exciton if the thickness of the red emittinglayer 100 is too thin while the driving voltage is increased if thethickness of the red emitting layer 100 is too thick. However, forthicker red emitting layers, a material having better charge carryingcapability can be used since the increase in driving voltage is notunreasonably high.

The thickness of the green emitting layer 200 is preferably 100 to 1,000Å. The emission efficiency is lowered due to an insufficientrecombination region for the exciton if the thickness of the greenemitting layer 100 is too thin while driving voltage is increased if thethickness of the green emitting layer 100 is too thick. However, theinvention can also be applied to a currently known emitting layer, and amaterial having good charge carrying capability can be used even in thehigher thickness range since the increase in driving voltage is notunreasonably high.

A blue emitting layer 300 is formed by coating a blue fluorescenceemitting material as a common layer over the entire substrate afterforming the red and green layers using phosphorescence emittingmaterials. The patterning process is simplified since the bluefluorescence emitting material is coated on an upper part of the red andgreen regions so that it is not necessary to finely pattern the blueemitting region. A full color organic electroluminescent device of thepresent invention has superior stability compared to an existing fullcolor organic electroluminescent device since the emitting materialdegrades less because the blue emitting material is coated on the frontsurface of the substrate.

Although the thickness of the blue emitting layer 300 should beoptimized according to the color coordinates and emission efficiency ofred, green and blue, the thickness of the blue emitting layer 300 ispreferably 500 Å or less since the driving voltage of the red and greenpixels increases, and the color coordinates of the red and green pixelsare changed if the thickness of the blue emitting layer 300 is 500 Å ormore.

The blue emitting layer can be formed of blue fluorescence emittingmaterial. Preferably, the blue fluorescence emitting material is a smallmolecular material selected from the group consisting of DPVBi,spiro-DPVBi, spiro-6P, distylbenzene (DSP) and distyrylarylene (DSA),and small molecular materials formed of two or more host/dopantmaterials selected from the group consisting of DPVBi, spiro-DPVBi,spiro-6P, distylbenzene (DSP) and distyrylarylene (DSA), or a polymericmaterial selected from PFO based polymer and PPV based polymer.

Meanwhile, a blue emitting material having a larger energy band gap thanthe red emitting material and the green emitting material can also beused as the blue emitting material. Preferably, the blue emittingmaterial has a HOMO value of at least |5.5 eV|.

While according to the present invention, there is a possibility ofcolor mixing as the blue emitting material is coated on an upper part ofthe red and green regions, color purity is not deteriorated by the colormixing in a full color organic electroluminescent device of the presentinvention since the emitting wavelength is maintained in the preferablewavelength range by limiting the emitting range of the red and green tothe emitting layer of red and green only so that the blue emitting layerdoes not contribute to emission in the red and green regions.

A full color organic electroluminescent device is completed by formingan electron transport layer 22 in an ordinary manner, and optionally, anelectron injection layer which is not shown in the figure can be furtherintroduced on the electron transport layer 22, coating an upperelectrode 24 on an upper part of the electron transport layer and/or anelectron injection layer over the entire substrate and sealing the upperelectrode coated on the electron transport layer and/or the electroninjection layer.

Examples of the present invention are suggested as follows. However, thefollowing test examples are provided only to help understand the presentinvention well, and the present invention is not limited to thefollowing test examples.

Example 1

A hole injection layer having thickness of 30 nm formed of4,4′,4″-tris(N-3-methylphenyl)-N-phenylamino)triphenylamine (MTDATA,Sensient Imaging Technologies GmbH) and a hole transport layer havingthickness of 30 nm or less formed ofN,N′-di(naphthalen-1-yl)-N,N′-diphenyl-benzidine (NPB) were formed on apatterned test cell. A red phosphorescence emitting layer was patternedand formed to a thickness of 35 nm from a host of CBP manufactured byUDC Corporation, doped with a dopant of R7 manufactured by UDCCorporation to a concentration of about 10%. A blue fluorescenceemitting layer 10 nm thick was formed by doping a blue fluorescenceemitting material of IDE 120 (manufactured by Idemitsu Corporation),with a DPVBi type dopant (Idemitsu Kosan) and applying the material toan upper part of the patterned red phosphorescence emitting layer andover the entire test cell. The red phosphorescence emitting layer wasformed and patterned by laser induced thermal imaging. The test cell wascompleted by laying up Alq3 manufactured by New Japanese Iron ChemicalCorporation as an electron transport layer to a thickness of 20 nm onthe patterned red phosphorescence emitting layer, depositing the cathodeon the electron transport layer and sealing the cathode deposited testcell using glass. The color coordinates of the completed test cell weremeasured.

Example 2

A hole injection layer having a thickness of 30 nm formed of(4,4′,4″-tris(N-3-methylphenyl)-N-phenylamino)triphenylamine (MTDATA,Sensient Imaging

Technologies GmbH) and a hole transport layer having a thickness of 30nm or less formed of N,N′-di(naphthalen-1-yl)-N,N′-diphenyl-benzidine(NPB) were formed on a patterned test cell. A green phosphorescenceemitting layer was patterned and formed with a thickness of 20 nm from ahost of CBP manufactured by UDC Corporation, doped with a dopant ofIrPPy manufactured by UDC Corporation to a concentration of about 5%. Ablue fluorescence emitting layer 10 nm thick was formed by doping a bluefluorescence emitting material, IDE 120 (manufactured by IdemitsuCorporation), with DPVBi type dopant (Idemitsu Kosan) and applying thematerial to an upper part of the patterned green phosphorescenceemitting layer and over the entire test cell. The green phosphorescenceemitting layer was formed and patterned by laser induced thermalimaging. The test cell was completed by laying up Alq3 manufactured byNew Japanese Iron Chemical Corporation as an electron transport layer toa thickness of 20 nm on the patterned green phosphorescence emittinglayer, depositing the cathode on the electron transport layer andsealing the cathode deposited test cell using glass. The colorcoordinates of the completed test cell were measured.

Comparative Example 1

A hole injection layer having a thickness of 30 nm formed of(4,4′,4″-tris(N-3-methylphenyl)-N-phenylamino)triphenylamine (MTDATA,Sensient Imaging Technologies GmbH) and a hole transport layer having athickness of 30 nm or less formed ofN,N′-di(naphthalen-1-yl)-N,N′-diphenyl-benzidine (NPB) were formed on apatterned test cell. A red phosphorescence emitting layer was patternedand formed with a thickness of 35 nm from a host of CBP manufactured byUDC Corporation doped with a dopant of R7 manufactured by UDCCorporation to a concentration of about 10%. The red phosphorescenceemitting layer was formed and patterned by laser induced thermalimaging. The test cell was completed by forming a hole inhibition layerof BAlq manufactured by UDC Corporation as a common layer to thicknessof 5 nm over the entire substrate, forming Alq3 manufactured by NewJapanese Iron Chemical Corporation as an electron transport layer to athickness of 20 nm on the hole inhibition layer, depositing the cathodeon the electron transport layer and sealing the cathode deposited testcell using glass. The color coordinates of the completed test cell weremeasured.

Comparative Example 2

A hole injection layer having a thickness of 30 nm formed of(4,4′,4″-tris(N-3-methylphenyl)-N-phenylamino)triphenylamine (MTDATA,Sensient Imaging Technologies GmbH) and a hole transport layer having athickness of 30 nm or less formed ofN,N′-di(naphthalen-1-yl)-N,N′-diphenyl-benzidine (NPB) were formed on apatterned test cell. A green phosphorescence emitting layer waspatterned and formed with a thickness of 20 nm from a host of CBPmanufactured by UDC Corporation doped with a dopant of IrPPymanufactured by UDC Corporation to a concentration of about 5%. Thegreen phosphorescence emitting layer was formed and patterned by laserinduced thermal imaging. The test cell was completed by forming a holeinhibition layer of BAlq manufactured by UDC Corporation as a commonlayer to a thickness of 5 nm over the entire substrate, laying up Alq3manufactured by New Japanese Iron Chemical Corporation as an electrontransport layer to a thickness of 20 nm on the hole inhibition layer,depositing the cathode on the electron transport layer and sealing thecathode deposited test cell using glass. The color coordinates of thecompleted test cell were measured.

The test results of the color coordinates of test examples 1 and 2 andcomparative examples 1 and 2 are represented as in the following table1.

TABLE 1 CIE x CIE y Test example 1 0.63 0.34 Test example 2 0.33 0.61Comparative example 1 0.64 0.33 Comparative example 2 0.33 0.61

As seen in the table 1, there is hardly any red emission color puritydifference between the test Example 1 according to the present inventionand Comparative Example 1 which used a red phosphorescence emittingmaterial and a hole inhibition layer. Furthermore, it can be seen thatthere is hardly any green emission color purity difference between thetest Example 2 according to the present invention and ComparativeExample 2 which used a green phosphorescence emitting material and ahole inhibition layer.

FIG. 5 is a graph showing the relationship between bias voltage andluminance applied for test cells fabricated according to test Example 2and Comparative Example 2, and FIG. 6 is a graph showing therelationship between bias voltage and current density applied to testcells fabricated according to test Example 2 and Comparative Example 2.

Referring to FIGS. 5 and 6, it can be seen that the test cell accordingto the embodiment of the present invention as shown in Example 2 has alower bias voltage compared to the test cell of Comparative Example 2for a given luminance and a given current density.

As described above, a full color organic electroluminescent device ofthe present invention simplifies the deposition process since it is notnecessary to form a hole inhibition layer that would otherwise berequired to prevent holes from diffusing from the phosphorescenceemitting device to the electron transport layer as the blue fluorescenceemitting layer is applied as a common layer on an upper part of the redand green phosphorescence emitting layers. The device of the inventionalso reduces the number of steps required in manufacture since theemitting layer requires only two patterning steps to produce a fullcolor organic electroluminescent device of the present invention whilethe emitting layer of an existing organic electroluminescent devicerequires three patterning steps.

While the invention has been particularly shown and described withreference to preferred embodiments thereof, it will be understood bythose skilled in the art that changes in form and detail may be madetherein without departing from the spirit and scope of the invention.

1. A method for fabricating a full color organic electroluminescentdevice comprising: forming a first electrode pattern on a substrate;forming a hole transport layer over the substrate and the firstelectrode pattern; applying red and green phosphorescent emittingmaterial over the red and green pixel regions, respectively; applying ablue emitting layer to the substrate covering the blue pixel regions andthe red and green phosphorescent emitting materials; and forming anupper electrode over the blue emitting layer.
 2. The method forfabricating a full color organic electroluminescent device according toclaim 1 further comprising: forming an electron transport layer betweenthe blue emitting layer and the upper electrode.
 3. The method forfabricating a full color organic electroluminescent device according toclaim 2, wherein the red phosphorescence emitting material comprises adopant provided in an amount from 7 to 15%.
 4. The method forfabricating a full color organic electroluminescent device according toclaim 3 wherein the dopant is a first dopant and the greenphosphorescence emitting material comprises a second dopant provided inan amount from 5 to 10%.
 5. The method for fabricating a full colororganic electroluminescent device according to claim 1, wherein the blueemitting material is a blue fluorescence emitting material.
 6. Themethod for fabricating a full color organic electroluminescent deviceaccording to claim 5, wherein the blue fluorescence emitting material isa small molecular material selected from the group consisting of DPVBi,spiro-DPVBi, spiro-6P, distylbenzene (DSP) and distyrylarylene (DSA), asmall molecular material formed of two or more materials of host/dopantselected from the group consisting of DPVBi, spiro-DPVBi, spiro-6P,distylbenzene (DSP) and distyrylarylene (DSA), or a polymeric materialselected from PFO based polymer and PPV based polymer.
 7. The method forfabricating a full color organic electroluminescent device according toclaim 1, wherein the thickness of the red and green phosphorescenceemitting layers is from 100 to 1,000 Å.
 8. The method for fabricating afull color organic electroluminescent device according to claim 1,wherein the thickness of the blue emitting layer is 500 Å or less. 9.The method for fabricating a full color organic electroluminescentdevice according to claim 1, wherein the red and green phosphorescenceemitting materials are formed by a method selected from the groupconsisting of vacuum deposition, wet type coating, ink jet printing andlaser induced thermal imaging.
 10. The method for fabricating a fullcolor organic electroluminescent device according to claim 1, whereinthe blue emitting material is formed by wet type coating or vacuumdeposition